The invention relates to a macrolens having a distance setting ring rotatively supported on a lens mount, a lens component sliding longitudinally therethrough along the lens axis, and a diaphragm drive.
This type of macrolens has a known disadvantage in that the diaphragm ring must be operated manually while making reference to filter factor tables to determine a relation to the image scale. In many lenses, such a table is cut directly onto the lens barrel. Such a manual setting of the aperture, however, makes fast setting of the distance with a corresponding correct aperture setting to be practically impossible, especially in a movie camera. Moreover, only a few values can be accurately set when such tables are used, and the values lying therebetween must be estimated.
The invention has as its object the provision of a macrolens of the above-mentioned type, with which the aperture values corresponding to the focusing can be set automatically by means of a distance setting ring.
According to the invention, this object is achieved by providing a diaphragm drive on the longitudinally sliding lens component, and connecting the diaphragm drive by means of a diaphragm drive pin, to a converter mounted on the lens mount. This converter can be formed, for example, by a guide slot extending at an angle to the lens axis, which converts the longitudinal motion of the lens component into a rotational motion of the diaphragm drive pin. This extremely simple construction allows a fully automatic and smooth procedure and ensures absolute reliability in obtaining the correct exposure values for any desired distance setting. This results in the special advantage that, even with macrolenses of a movie camera, fast distance settings with the correct exposure values can be performed. To accomplish this objective, the converter must be so designed that, as the lens component slides along its axis by X mm, the diaphragm drive pin is displaced by set stop values corresponding to the change of distance. This conversion need not necessarily be a linear relation, so that the guide slot need not necessarily be straight lines.
Another variation of the invention is that the converter is formed by a diaphragm sleeve, which has many advantageous characteristics. First, the diaphragm sleeve is rotatively supported between the lens component and a lens barrel. The diaphragm sleeve is connected to the diaphragm drive pin; the diaphragm sleeve has a guide pin--non-rotatively fitted into a guide slot provided on the interior of the lens mount--located in the end section of the diaphragm sleeve opposite the diaphragm drive pin. The advantage of such a variation is that the converter is transferred from the spatially confined area of the diaphragm drive, and the lens component located in the lens barrel, to the free region between lens cap and lens.
Another variation of the invention is that the diaphragm ring is rotatively connected to the rotatively supported diaphragm sleeve coaxially to the lens axis via the guide slot or longitudinal slot, which extends at an angle to the lens axis. Such an approach enables automatic aperture control by the converter, as well as manual aperture control by the diaphragm ring, as before.
Yet another variation of the invention has the diaphragm sleeve mounted in radial direction coaxially inside the correction sleeve, and has a conical extension of the diaphragm sleeve in the range thereof. This conical extension of the diaphragm sleeve has no deleterious effect on the incidence of light on the lens component.
Another variation of the invention uses a no-sag spring mounted in the interface between the correction sleeve and the lens mount. The spring counteracts the reactive force exerted by the guide pin on the correction sleeve as the guide pin moves in the guide slot. This variation ensures that, as the lens component moves along its axis, causing the diaphragm sleeve to move along its axis, the converter, which is formed by the longitudinal slot in the correction sleeve and the guide pin on the diaphragm sleeve, provides the rotation of the diaphragm sleeve together with the diaphragm drive pin, without rotation of the correction sleeve. The increased friction caused by the no-sag spring can be easily overcome by the manual setting of the aperture values.
Another variation of the invention is that the converter is formed by a groove located on the diaphragm sleeve which extends longitudinally through the lens component and at an angle to the lens axis, in which groove is guided a guide pin connected to the diaphragm ring or to the lens mount. Such a variation of the invention is as practicable and purposeful as the converters described earlier.
Note that the aforementioned construction of the converter cannot be used in all lenses.
Present-day lenses are operated with "floating elements". They have several lens components which, during focusing, may move at different speeds, or may be stationary. Many times, the aperture is connected to the stationary lens component, so that no correction movement can be derived from the diaphragm sleeve coupled therewith.
In this case, it is advantageous to control the correction by another lens component, which is usually the first lens component that is turned toward the lens. In a modification of the invention involving the use of lenses relating to the invention, there may be provided, as a converter inside the lens mount, two coaxially extending sleeves that are fitted into each other and each of which is formed with a longitudinal slot: one sleeve is connected to the diaphragm drive pin coupled to the aperture, whereby its longitudinal slot is provided at an angle to the lens axis; the other sleeve is connected to a manually adjustable diaphragm ring, whereby its longitudinal slot is provided parallel to the lens axis. A follower pin connected to a longitudinally adjustable lens is passed through both longitudinal slots.
Using this special construction, the appropriate aperture control can be carried out advantageously with automatic and smooth focusing, so that faulty aperture settings can be avoided. The follower pin connected to the lens component and passing through both longitudinal slots causes the rotation of the sleeve connected to the diaphragm drive, and which has its longitudinal slot at an angle toward the lens axis. The angle of this longitudinal slot with respect to the lens axis is such that the longitudinal displacement of the lens component corresponds to the amount of correction necessary to obtain the correct aperture value at the new distance setting. The displacement path defined by the longitudinal slot at an angle to the lens axis need not necessarily be a linear line corresponding to a linear stop setting. In the case of a nonlinear ratio between distance setting and stop setting, especially in lenses with lens components that move relatively to each other, the longitudinal slot may also be formed as an appropriate curve.
One variation of the invention provides that the radially outer sleeve is rotatively connected to the diaphragm ring, and the radially inner sleeve, which is connected to the diaphragm drive pin, is rotatively supported within the outer sleeve, and the follower pin is rotatively supported on the lens component. By virtue of this construction, the diaphragm setting for the chosen exposure can be manually set, whereby the rotational motion is transferred from the diaphragm ring to the outer sleeve, from the outer sleeve by means of the follower pin to the inner sleeve, and from the inner sleeve to the diaphragm drive. Since the follower pin is rotatively supported, this rotational motion can be carried out independent of the particular longitudinal position of the follower pin or of the lens component.
Another variation of the invention provides that the largest tangential distance between the two longitudinal slots be formed such as to correspond to the largest possible path of adjustment of the diaphragm drive pin, the length of the longitudinal slots corresponding to the largest possible longitudinal path of adjustment of the lens component. Such a formation of the longitudinal slots ensures the automatic conversion of the longitudinal motion of the lens component into a rotational motion throughout the entire region for distance setting.
Another variation of the invention provides that a no-sag spring or highly viscous grease be placed between the end face of the radially outer sleeve and the lens mount. This structure makes it more difficult for the outer sleeve--and easier for the inner sleeve--to turn. In this way, it is ensured that the follower pin, as it is moving in the longitudinal slots along its axis, forces the inner sleeve to rotate, while the reactive force exerted by the inner sleeve on the follower pin, which transmits the reactive force to the outer sleeve, is absorbed by the no-sag spring or by the highly viscous grease, thereby preventing the outer sleeve from rotating.
Finally, another variation of the invention consists of mounting both longitudinal slots and the guide pin in symmetric relation to a longitudinal symmetry plane of the lens. This double arrangement of diametrically opposed guide slots and follower pins results in a uniform transfer of forces and, thereby, an accurate diaphragm setting.